This invention relates to an improved annular parachute intended for low altitude deployment of troops at a low rate of descent. A unique system is employed to rapidly inflate the parachute without disastrous overinflation which may lead to such malfunctions as canopy inversions and canopy collapse and without generating excessive opening forces.
It has been found desirable to drop military personnel and military equipment from the lowest possible altitude and at the maximum horizontal velocity in order to reduce exposure to enemy fire. The increased load which today's troops must carry with them when they jump requires that any new parachute must provide a high drag coefficient so as to land the paratrooper at a safe velocity.
The annular ring parachute canopy discussed herein may be compared in configuration to a doughnut having a main vent or opening in the middle. The main vent or opening is covered with netting which does little to impede the passage of air but does prevent other parachutists from becoming entangled in the parachute below them. The problem with prior art annular canopies is that the relatively large central vent allows air to escape almost as quickly as it enters the parachute. This passage of air results in the canopy being slow to inflate with full inflation not being attained until a low critical velocity is reached. Due to the low altitude, from which these parachutes are intended to be dropped, rapid canopy inflation is a necessity.
It has been found that rapid inflation can be achieved by a unique mechanism which holds the main vent closed until the canopy has had a chance to fill with air. This parachute opens rapidly without an opening shock or snap which may lead to canopy inversions and other difficulties such as the failure of parachute lines or canopy materials.